The present invention relates to network interfacing, and more particularly to a novel network transceiver that steers network data streams to a selected data path compatible with the operating speed of a network link partner.
A Local Area Network, or (LAN), is a communications systems that provides a connection among a number of independent computing stations within a small area, such as a single building or group of adjacent buildings. One type of network structure uses one or more repeaters in a star topology, with each repeater having several ports. A data packet received at one port is retransmitted to all other ports of the repeater. Each repeater in turn restores timing and amplitude degradation of data packets received at one port and retransmits the packets to all other ports.
Traditional Ethernet networks (10BASE-T) operate at 10 Mb/s Ethernet protocol, as described by IEEE Standard 802.3; the majority of Ethernet interfaces currently operate at this data rate. However, a newer Ethernet standard, under IEEE standard 802.3 u, accomplishes the faster operation of 100 BASE-T systems, at a 100 Mb/s data rate (i.e., a 125 Mb/s encoded bit rate) using unshielded twisted pair (UTP) physical media. The 100 BASE-T standard defines operation over two pairs of category 5 UTP (100 BASE-TX) and over four pairs of category 3 UTP. The 100 BASE-FX network medium, covered by the 100 BASE-T standard, allows operation over dual fiber optic cabling.
Ethernet protocol provides for a Media Access Control (MAC), enabling network interface devices at each network node to share accesses to the network medium. One type of connection, termed a Media Independent Interface, or MII, connects the MAC to a physical layer (PHY) transceiver configured for a particular network medium, e.g., 10 BASE-T, 100 BASE-FX, or 100 BASE-TX. The physical layer transceiver is configured for converting the MII protocol signals output by the MAC into analog network signals, such as Multiple Layer Transition-3 (MLT-3) signals for 100 Mb/s Ethernet networks, or Manchester-encoded signals for 10 Mb/s Ethernet networks. (Networks often use several PHY devices operating over different media types.)
Ethernet switches have multiple interfaces, each capable of either 10 Mb/s or 100 Mb/s operation, and are able to be connected in communication with a link partner operating at a corresponding data rate. Because a switch allows multiple simultaneous traffic between its ports, it is possible to allow the ports to operate a different speed relative to each other. A repeater, on the other hand, is configured to operate at only a single data rate. A 10 Mb/s repeater, for example, cannot be placed in communication with a link partner operating at 100 Mb/s. Moreover, the vast majority of Ethernet interfaces in today""s networks operate only at 10 Mb/s, hence are unable to communicate with a repeater or switch that operates only at 100 Mb/s.
A 10/100 Mb/s switch is defined as one in which each switch port has a means of negotiating the speed of operation with a link partner connected to the port via a network medium. Auto-negotiation is performed by the switch as a link startup procedure each time a link to the switch port is connected, powered on or reset. During auto-negotiation, the switch automatically configures the link partner according to network configuration parameters; if the link partner cannot run at 100 Mb/s, the switch configures the link to run at 10 MB/s.
Repeaters are more economical than switches. But the limitation in operating speed versatility of a repeater makes it unsuitable in operating environments where it is necessary to adapt to the data rate of a link partner. It would be desirable to provide a repeater or repeater system having the variable data rate attributes of a switch. To achieve this objective, the invention implements automatic steering of a network data stream to a selected repeater interface having a data rate operating at the same data rate as the link speed of the network link partner.
The invention provides a novel method of operating repeaters or other hub devices in a local area network, such as one conforming to Ethernet protocol, in which there are a one or a plurality of repeaters having repeater interfaces operating at respectively different data rates for communicating with a link partner on a network medium. The methodology comprises determining the data rate link speed of the link partner, and based on that data rate, and automatically multiplexing data between the network medium and a selected one of the repeater interfaces.
In accord with one aspect of the invention, a network transceiver is configured for supplying network data, transported via a network medium between a link partner, to a selected repeater interface. The network transceiver includes an auto-negotiation unit for determining a link speed of the link partner via the network medium. The network transceiver also includes first and second data busses for providing data communication with first and second repeater interfaces at respective data rates, and a multiplexer circuit. The multiplexer circuit is configured for supplying the network data between the network medium and a selected one of the first and second data busses for data communication with the corresponding selected repeater interface at the corresponding data rate, based on the determined link speed of the link partner. Use of the multiplexer circuit and the first and second data busses enables the network data from one or a plurality of link partners to be automatically supplied (i.e., steered) to the appropriate repeater interface, based on the corresponding link speed of the link partner. The repeater interfaces may be implemented in separate repeaters operating at respective data rates, or in an integrated repeater having two separate data rate domains.
In accordance with another aspect of the invention, a repeater em comprises first and second repeater interfaces outputting network data at respective data rates, and a network transceiver. The network transceiver is configured for supplying the network data to at least one link partner via a corresponding network medium. The network transceiver includes a multiplexer circuit for supplying the network data between a selected one of the first and second repeater interfaces and the link partner according to a determined link speed of the link partner. Hence, the link partner is automatically connected to the appropriate repeater based on the determined link speed, enabling different speed network nodes to be connected by the network transceiver.
Still another aspect of the invention provides a method of supplying network data between repeater interfaces having respective data rates a network medium providing communication for a link partner. The method comprises determining a link speed of the link partner on the network medium, and connecting the link partner to a selected one of the repeater interfaces based on the determined link speed of the link partner. Hence, the link partner is automatically connected to a selected repeater interface, ensuring compatibility between network components having different data rate capabilities.
Various objects and features of the present invention will become more readily apparent of those skilled in the art from which the following description of a specific embodiment thereof, especially when taken in conjunction with the accompanying drawings.